Literature in data privacy. The concept of data privacy was first rigorously quantified by an important framework called differential privacy (DP), which was first introduced in [1]}, [2]}. The definition of DP has become a de facto standard for data privacy in both academic and industrial practice. We refer the interested readers to [3]}, [4]} for comprehensive reviews. Based on this concept, different theories and techniques have been developed, such as the technique of tree-based aggregation [5]}, which is used in the design of our algorithm CPPQ, and the mechanism of random perturbation (see e.g., [3]}), which is an important component in the design of both CPPQ and LPPQ.
